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LinuxCAD User Interface Getting Started Tutorial.

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Right after you have installed LinuxCAD using installation program the main program executable located in C:\usr\linuxcad\linuxcad.exe(on Windows) or in /usr/linuxcad/linuxcad(on Linux). The user guide is located in C:\usr\linuxcad\userguide.html(on Windows) or /usr/linuxcad/userguide.html(on Linux). Please read along the user manual until you feel comfortable to start.

Some people prefer to skip reading manuals, that is why this web page even if you do not read manuals PLEASE READ THIS PAGE. It is absolutely essential for working with LinuxCAD.


LinuxCAD User Interface consists of:

  1. Command area below the graphics area where you can enter commands as text,
  2. Pull down menus, which are the primary user interface now (until we come up with something better),
  3. Buttons in the top right corner of LinuxCAD window, there are 3 buttons: "+", "-" and "S"(on Linux only) . They are tied to the commands ZOOMPLUS, ZOOMMINUS and the S button allows you to start command script.

To interact with LinuxCAD you should select command from the pull down menu and reply to messages that appear in command line by entering accptable for LinuxCAD input which may be: Points, Object, Keywords.

Typing ENTER or SPACE will end your input and transfer control to LinuxCAD, you will find yourself pressing space often when working with LinuxCAD.


   Left Mouse Button -  Logical YES. Means: enter point when 
                               LinuxCAD expects point or Grab the Object
                               when LinuxCAD expects object.

   Right Mouse Button - Logical NO. Means: cancel my input, I'd like
                               to cancel this command or I'd like to finish
                               selecting objects.


"Keys" - menu is special it contains options or keywords available for the command that is currently executing.



Controlling and Giving Commands to LinuxCAD


LinuxCAD accepts all commands through a command line. Entering commands, points and scalars from the command line produces drawing output in the graphics area of the LinuxCAD. You can execute commands either by manually typing them or through pull down menus.

In many of the commands described below you will be asked to enter objects. The LinuxCAD prompt for entering objects looks like this:

Select objects:

You can select objects by choosing individual objects or by selecting a group using the Window frame or the Crossing frame. To switch to the Window frame group selection mode just type "W" ( do not type quotes ).

To switch to the Crossing frame group selection mode type "C" . A specific set of objects is affected by every command. This set is referred to as the selection set and will be highlighted. There are two modes of LinuxCAD operations when you create a selection set. The first mode is ADD mode, when objects are added to the selection set. Another mode is REMOVE when objects are removed from the selection set. For instance, when an object is selected (which we will call B1) for deletion by the ERASE command you may cancel the delete of B1 by switching the selection set from ADD mode to REMOVE mode. Now, once in REMOVE mode B1 can be unhighlighted by picking it with the mouse.

To switch in REMOVE mode enter "R" at the Select object: prompt. To switch back to the ADD mode enter "A" at the Select object: prompt. The initial mode is of course ADD. For your convenience object selection keywords can be accessed from the pull down menu: ***/Select objects You can enter points as coordinate pairs X and Y in two distictly different coordinate systems (x,y) and polar (angle, radius), points in both systems can be entered as absolute or as relative to a previous location.
 
  Example:  X,Y         
  
  A comma must separate x from y. Do not use spaces.   
  
  Sometimes you may want to enter a point as a displacement from the previous  
  
 point. In that situation you enter the "at sign"  ("@") in front of the coordinate pair.  
  
  For instance:  
  
    @10,20  -  says we want a point 10 units above the previous point and 20 units  
  
 to the left from previous point.  
  
    @45<1.125  - says we want a point in the direction of 45 degrees 1.125 inches  
  
away from the previous location.  
  
   X,Y - absolute Decarte point  
   A < R - absolute polar point  
   @X,Y - relative Decarte point  
   @A < R - relative polar point  
  


You can enable ORTHO mode any time by selecting Ortho/On in the pull down menu.

ORTHO mode will only allow drawing of vertical or horizontal lines. In order to draw skewed lines, disable ORTHO. In addition to ORTHO, LinuxCAD allows you to control drawing with other modes. For example, by setting SNAP mode on, movement of the cross hair is now discrete with a particular fixed step. GRID mode will show you a constant Cartesian grid overlaying your drawings.

It is very convenient to start or end a line at a very specific position in relation to other objects in the drawing. For example, you might want to start another line from the exact middle of another vector or from the intersection point of two objects. This is possible. LinuxCAD provides an object attachment feature.

You can attach to the end point, the intersection point, the middle point and to a perpendicular projection of the previous point to an object.

Any time LinuxCAD expects you to enter point, you may enter an object attachment keyword first and the point second.

All object attachment keywords can be found in the ***/Osnaps pull-down menu. Here they are: NEA, END, PER, INT, TAN, MID, CEN, VER, EDG, POI.

 
        2D object attachments
   NEA   -  Nearest point on a line of an object.
   END   -  End point of a line.
   INT   -  Intersection point of two lines.
   PER   -  Draws perpendicular from the previous point to the object you picked.
   TAN   -  Tangent to arcs,ellipses and circles, runs tangent from the prevous 
            point to the object you picked.
   MID   -  Middle point of line segments.
   CEN   -  To the center of arcs,lines,ellipses.

        3D object attachments
   VER   -  To one of the end points of a 3D object.
   EDG   -  3D middle point of a rib of 3D wireframe object.
   POI   -  Attachement that is using point on 3D line.
  

When customizing environment variables it is important to know color numbers.

 
   LinuxCAD standard color numbers are:  
  
 BLACK     0  
 RED       1  
 YELLOW    2  
 GREEN     3  
 CYAN      4  
 BLUE      5  
 MAGENTA   6  
 WHITE     7  
 LIGHTRED  8  
  
  In all commands you can enter either one of the colors above or a 
 color as a combination of RGB values. But in dim variables you must 
 specify one of the standard LinuxCAD colors above.